1. Field Of The Invention
The present invention relates to a ladder apparatus and more particularly to such an apparatus which is adjustable in such a manner as to permit it to be deployed securely in support of the ladder portion thereof in upstanding position in a wide variety of operative environments, which incorporates a work platform and which can conveniently and expeditiously be collapsed for transport and storage.
2. Description Of The Prior Art
The use of elongated ladders of fixed or adjustable length to reach elevated work areas has long been known. While such ladders have proved satisfactory for use in a variety of work environments, there are a host of other environments in which they cannot be used, or can only be used with the exercise of great care. A number of factors, such as the location and makeup of the work area and functional limitations inherent in the structure of the ladder itself, contribute to such limited utility.
One well recognized deficiency in most conventional ladders is that, due in large part to the narrow transverse dimensions of their bases, the ladders are susceptible to lateral slippage when in use. Such slippage can occur, for instance, due to an unbalanced lateral distribution of the weight of the user on the ladder or of equipment or supplies supported on the ladder. This problem is exacerbated in instances in which the upper ends of the ladders are rested against substantially smooth surfaces which provide minimal frictional resistance to sliding of the upper portions of the ladders laterally therealong.
A similar limitation in conventional ladders is the susceptibility to slippage of the base portions thereof away from the work area, particularly on hard, smooth surfaces such as concrete walks, driveways, foundations and the like. Under such conditions, the ladders may slide completely out from under the user.
Yet another problem encountered in the use of conventional ladders is that the work areas in which they must be deployed are frequently not suitable in that, for example, there are no substantially flat surfaces upon which to rest the base portions of the ladders or walls against which to rest the upper portions of the ladders. Positioning of the ladders on irregular or uneven surfaces not only increases the hazard for the ladders to slip in the manners heretofore described, but also to twist substantially about their longitudinal axis when mounted by the users thereof.
In still other instances, there are no vertical surfaces against which the upper portions of the ladders can be rested. There may be no vertical surfaces available for use, or those surfaces which are present may be unsatisfactory because they are in need of repair or they may be constructed of fragile materials such as glass or light-gauge aluminum which might be damaged.
A number of attempts have been made in the prior art to overcome these and other deficiencies. Such attempts by the prior art generally fall into two broad categories: ladder assemblies comprising ladder portions of substantially conventional design having stabilizing structures unitary therewith; and auxiliary stabilizing apparatuses adapted for attachment on ladders of conventional design. While such prior art efforts are adequate within the scope of their design to eliminate or minimize one or more of the limitations attendant upon the use of conventional extension ladders, each is deficient in one or more respects. For example, in such prior art ladder assemblies and attachments which employ legs for support, there is an inherent difficulty in controlling the positions of the legs. Prior art devices which use chains and the like in an attempt to limit movement of the legs are inefficient, cumbersome and easily entangled.
Yet another problem encountered in the use of conventional ladders is that none of the prior art ladders of which applicant is aware provide a surface deployable for the support of heavy equipment or the user thereof. While some stepladders have small collapsible shelves, they are incapable of supporting substantial weight or having a surface area sufficient for the deposit of more than a few small items thereon.
Therefore, it has long been known that it would be desirable to have a ladder apparatus which has the ability to be used in a wide variety of operative environments and under the most adverse conditions while securely and dependably supporting a person thereon; which has a support platform which can be deployed to support a person or relatively heavy equipment; and which can rapidly and conveniently be collapsed for transport and storage.